Acid and Bases: An Introduction. Properties of Acids 1. Sour taste 2. Can produce H + (hydrogen)...
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Transcript of Acid and Bases: An Introduction. Properties of Acids 1. Sour taste 2. Can produce H + (hydrogen)...
Acid and Bases: An Introduction
Properties of Acids
1. Sour taste
2. Can produce H+ (hydrogen) ions (protons)
3. Change the color of litmus from blue to red
4. Reacts with metals such as Zn and Mg to produce H2 gas. Ba(s) + H2SO4 BaSO4(aq) + H2(g)
5. Reacts with carbonates (CO32-)to produce CO2
NaHCO3(s) + CH3COOH(aq) NaCH3COO(aq) + H2O(l) + CO2(g)
6. Acids conduct an electric current
Properties of Bases
1. Bitter or caustic taste2. A slippery, soapy feeling3. Can produce OH- (hydroxide) ions4. Ability to change litmus from red to blue5. Bases conduct an electric current6. Bases react with acids to produce a salt and water.
This is known as a neutralization reaction. HCl + NaOH NaCl + H2O HCl + Mg(OH)2 MgCl2 + H2O
acid base salt water
Ions in Solution
Acidic solutions contains more hydrogen (H+) ions than hydroxide ions (OH-) pH < 7
Basic solutions contains more hydroxide ions (OH-) than hydrogen ions pH > 7
Neutral solutions contain an equal concentration of hydrogen and hydroxide ions pH = 7
Question Time
What are the properties of acids? What are the properties of bases? What ion does an acid typically produce? What ion does a base typically produce? What is the OH- ion called? If there are more H+ ions than OH-, is the solution
acidic, basic, or neutral? What if there are an equal number of H+ and OH-
ions?
Three Definitions of Acids/Bases
Type Acid Base
Arrhenius H+ producer OH-producer
Bronsted-Lowry H+ donor H+ acceptor
Lewis Electron-pair acceptor
Electron-pair donor
Bronsted-Lowry Conjugate Acid/Base
HX(aq) + H2O(l) ⇆ H3O+(aq) + X-(aq)
acid base Conjugate Conjugate
Acid Base
Conjugate acid is the substance produced when a base accepts a hydrogen ion from an acid
Conjugate base is the substance that the acid donates a hydrogen ion to form a base
Bronsted-Lowry Conjugate Acid/Base
Conjugate acid-base pair consists of two substances related to each other by donating and accepting of a single hydrogen ion
NH3(aq) + H2O(l) NH4+ (aq) + OH-(aq)
base acid conjugate conjugate
acid base
Practice: Conjugate Acid and Conjugate Base
HCO3- + H2S ⇆ H2CO3 + HS-
H2PO4- + OH- ⇆ HPO4
2- + H2O
H2SO4 + NH3 ⇆ HSO4- + NH4
+
HC2H3O2 + H2O ⇆ H3O+ + C2H3O2-
Question Time
Name the three models of acids/bases. What is the Arrhenius model of acids/bases? What is the Bronsted-Lowry Model of Acid
bases? What is a conjugate acid and a conjugate base?
Question Time Identify the acid, base, conjugate acid, and conjugate base in
the Bronsted-Lowry reactions.
1. NH3 + H2O ⇆ NH4+ + OH-
2. H2O + CH3NH2 ⇆ OH- + CH3NH3+
3. HF + H2O ⇆ H3O+ + F-
4. HCOOH +CN- ⇆ HCOO- + HCN
5. NH4+ + CO3
2- ⇆ NH3 + HCO3-
Water in Acid/Base solutions
Water and other substances can act as both acids and bases and are said to be amphoteric
Hydronium ion = H3O+ = H+ (Remember H+ is a proton)
H2O(l) + H2O(l) ⇆ H3O+(aq) + OH-(aq)
Monoprotic and Polyprotic Acids
Monoprotic acid donates one hydrogen ion Polyprotic acid donates more than one
hydrogen ion
Question Time
What is a Lewis acid? What is a Lewis base? What is the H3O+ ion called? What is the shorthand way to write H3O+? What is amphoteric? Give an example.
Clicker Time
Which is not a property of acids?
A. Changes litmus paper red to blue
B. Sour taste
C. Conducts an electrical current
D. Reacts with metal to product H2 gas
Clicker Time
Which is not a property of bases?
A. Changes litmus paper red to blue
B. Sour taste
C. Feels slippery
D. Reacts with acids to product salt and water.
Clicker Time
What is an Arrhenius acid?
A. Hydrogen ion donor
B. Accepts an electron pair
C. Produces hydrogen ions
D. Produces a hydroxide
Clicker Time
What is a Bronsted-Lowry base?
A. Produces hydroxide ions
B. A hydrogen ion acceptor
C. An electron pair donor
D. Produces hydrogen ions
Clicker Time
What is a Lewis acid?
A. A hydrogen ion producer
B. A hydrogen ion donator
C. An electron pair acceptor
D. An electron pair donor
Clicker Time
HNO3 + H2O NO3- + H3O+
Which substance is the acid?
A. HNO3
B. H2O
C. NO3-
D. H3O+
Clicker Time
HNO3 + H2O NO3- + H3O+
Which substance is the conjugate base?
A. HNO3
B. H2O
C. NO3-
D. H3O+
Clicker Time
HCl + NH3 NH4+ + Cl-
Which substance is the base?
A. HCl
B. NH3
C. NH4+
D. Cl-
Clicker Time
HCl + NH3 NH4+ + Cl-
Which substance is the conjugate acid?
A. HCl
B. NH3
C. NH4+
D. Cl-